I agree. They do look nice. They also seem to get very good reviews.
Its is just that everyone looks 70+. Maybe in a few more years...
River cruises are also expensive enough and tied to cultural experiences sufficiently to prevent the riffraff from participating. You won’t see this clientele nor the ghetto buffoonery they inevitably bring with them. Worth every penny.
Ost of my 50+ cruises have been on Princess cruises (platinum status), Royal Caribbean (also platinum), some on Norwegian. Last 5 years I did a few Carnival sailings. Those are cheaper and does attract a different class of people. Especially their drink package is cheaper and bars are always crowded. Only thing good on carnival is food and desserts are pretty good. Last day on any cruise is much less stressful now compared to older days starting in 1988 for me. I prefer large Oasis class ships because the entertainment is better. They can afford to hire best shows with 6000+ passengers sharing cost. Surprising those mega ships are least crowded because there are a dozen restaurants to choose and 15+ bars on board. River cruise would be boring to me due to lack of high level production of daily shows.